洛谷 P7147 [THUPC 2021 初赛] 麻将模拟器 题解

Gavin

原题链接

碎碎念

目前写过最恶心的一道模拟题。

正文

本人写模拟题的习惯是先拟一个流程图,知道自己要写什么,避免在写代码的时候卡壳。

本题题面很清楚,看完基本就能构建出一个流程,所以下面直接把流程放上来了。

总流程如下:

  1. 初始化玩家
  2. 输入牌堆
  3. 发牌
  4. 进行回合

一个回合的流程如下:

  1. 摸牌(若刚吃、碰)则跳过。
  2. 判断自摸。
  3. 出牌。
  4. 若是功能牌,则立即生效。
  5. 判断是否荣和
  6. 判断能否碰
  7. 判断能否吃

这里对于其中几个较复杂的点进行详细说明。

和牌距离

这里参考了这篇题解的方法,非常感谢!

由于需要计算多次和牌距离,暴力枚举显然是不现实的,考虑 dp。

表示前种牌,已经组成个顺子或刻子、个对子的情况下,有对牌加上第种牌就可以组成顺子,副第种单牌。定义为我们需要组成的顺子或刻子的数量。

转移过程中,枚举作为当前这张牌选取的个数,由于我们需要第种牌组成新的顺子或差一张牌的顺子(就是上文表示的),所以

如果第张牌仍有剩余,组成刻子、对子或成为单牌。

直接将三种情况都判断一下就可以了。

一些错误

下面是本人写这道题时遇到的错误,放出来供大家自查 qwq。

  1. 不拥有特殊牌时才能和牌
  2. 不包含数字的种牌不能吃
  3. 用 sort 查找要出的牌会导致 TLE
代码
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/******************************
- @GavinCQTD / 2025-07-16 11:24:47
- "P7147 [THUPC 2021 初赛] 麻将模拟器" From Luogu
- # https://www.luogu.com.cn/problem/P7147
- 1000 ms / 512 MB
You have to love yourself.
******************************/

#include <algorithm>
#include <iostream>
#include <iterator>
#include <cstring>
#include <string>
#include <vector>
#include <queue>

constexpr int MAX_PLAYER=4,TILE_NUMBER=148,INITIAL_TILE_NUMBER=13;
const std::string TILES[38]={"","1M","2M","3M","4M","5M","6M","7M","8M","9M",
"1P","2P","3P","4P","5P","6P","7P","8P","9P","1S","2S","3S","4S","5S","6S",
"7S","8S","9S","E","S","W","N","B","F","Z","DOUBLE","REVERSE","PASS"};

class Tile{
protected:
std::string type;

public:
std::string getType(){
return type;
}

int getPriority(){
for(int i=1;i<=37;i++){
if(type==TILES[i]){
return i;
}
}
return 0;
}

bool isSpecialTile(){
return getPriority()>=35;
}

bool isNumberTile(){
return 1<=getPriority()&&getPriority()<=27;
}

int getNumber(){
return type[0]-'0';
}

bool operator==(Tile y){
return type==y.type;
}

bool operator!=(Tile y){
return !(*this==y);
}

Tile(){}
Tile(std::string _type):
type(_type){}
};

namespace Util{
Tile nextTypeTile(Tile tile){
return Tile(TILES[tile.getPriority()+1]);
}

Tile prevTypeTile(Tile tile){
return Tile(TILES[tile.getPriority()-1]);
}
}

class Tiles{
protected:
std::queue<Tile> tiles;

public:
void addTile(Tile tile){
tiles.push(tile);
}

bool canDraw(){
return !tiles.empty();
}

Tile draw(){
Tile front=tiles.front();
tiles.pop();
return front;
}

Tiles(){}
};

class Player{
protected:
std::string name;
std::vector<Tile> tiles;
std::vector<int> tileNumber;

public:
std::string getName(){
return name;
}

void addTile(Tile tile,bool output=true){
tiles.push_back(tile);
tileNumber[tile.getPriority()]++;
if(output){
std::cout << name << " IN " << tiles.back().getType() << "\n";
}
}

void draw(Tiles &_tiles){
addTile(_tiles.draw());
}

template<typename compareT>
std::vector<Tile>::iterator getTile(compareT compare){
std::vector<Tile> _tiles=tiles;
std::vector<Tile>::iterator result=_tiles.begin();
for(std::vector<Tile>::iterator it=std::next(_tiles.begin());it!=_tiles.end();it=std::next(it)){
if(compare(*it,*result)){
result = it;
}
}
return std::find_if(tiles.begin(),tiles.end(),[&](Tile tile)->bool{
return tile==*result;
});
}

void discard(std::vector<Tile>::iterator tile,bool output=true){
if(output){
std::cout << name << " OUT " << tile->getType() << "\n";
}
tileNumber[tile->getPriority()]--;
tiles.erase(tile);
}

void discard(Tile tile,bool output=true){
std::vector<Tile>::iterator it=std::find_if(tiles.begin(),tiles.end(),[&](Tile _tile)->bool{
return tile.getType()==_tile.getType();
});
discard(it,output);
}

int specialTileCount(){
return tileNumber[35]+tileNumber[36]+tileNumber[37];
}

int calculateDistance(){
static int dp[36][5][2][5][5];
memset(dp,0x3f,sizeof(dp));
dp[1][0][0][0][0] = 0;
int n=tiles.size()/3;
for(int i=1;i<=34;i++){
for(int j=0;j<=n;j++){
for(int k=0;k<=1;k++){
for(int x=0;x<=2&&x+j<=n;x++){
for(int y=0;y<=2&&x+y+j<=n;y++){
if(dp[i][j][k][x][y]<=14){
for(int c=x+y;c<=4;c++){
int l=c-x-y,w=dp[i][j][k][x][y]+std::max(0,c-tileNumber[i]);
if(l<=2){
dp[i+1][x+j][k][y][l] = std::min(dp[i+1][x+j][k][y][l],w);
}
if(l>=2&&!k){
dp[i+1][x+j][1][y][l-2] = std::min(dp[i+1][x+j][1][y][l-2],w);
}
if(l>=3&&x+j<n){
dp[i+1][x+j+1][k][y][l-3] = std::min(dp[i+1][x+j+1][k][y][l-3],w);
}
}
}
if(!Tile(TILES[i]).isNumberTile()||Tile(TILES[i]).getNumber()==1){
break;
}
}
if(!Tile(TILES[i]).isNumberTile()||Tile(TILES[i]).getNumber()==1){
break;
}
}
}
}
}
return dp[35][n][1][0][0];
}

int distanceAfterDiscard(Tile target){
discard(target,false);
int result=calculateDistance();
addTile(target,false);
return result;
}

int distanceAfterAdd(Tile target){
addTile(target,false);
int result=calculateDistance();
discard(std::prev(tiles.end()),false);
return result;
}

int distanceAfterPONG(Tile target){
discard(target,false);
discard(target,false);
int result=calculateDistance();
addTile(target,false);
addTile(target,false);
return result;
}

bool canPONG(Tile target){
return tileNumber[target.getPriority()]>=2&&distanceAfterPONG(target)<calculateDistance();
}

void PONG(Tile target){
std::cout << name << " PONG " << target.getType() << " " << target.getType() << " " << target.getType() << "\n";
discard(target,false);
discard(target,false);
}

int distanceAfterCHOW(Tile target,int type){
Tile tile1,tile2;
if(type==1){
tile1 = Util::nextTypeTile(target);
tile2 = Util::nextTypeTile(tile1);
}
else if(type==2){
tile1 = Util::prevTypeTile(target);
tile2 = Util::nextTypeTile(target);
}
else{
tile2 = Util::prevTypeTile(target);
tile1 = Util::prevTypeTile(tile2);
}

discard(tile1,false);
discard(tile2,false);
int result=calculateDistance();
addTile(tile1,false);
addTile(tile2,false);
return result;
}

int canCHOW(Tile target){
if(target.getNumber()<=7&&tileNumber[Util::nextTypeTile(target).getPriority()]>=1&&
tileNumber[Util::nextTypeTile(Util::nextTypeTile(target)).getPriority()]>=1&&distanceAfterCHOW(target,1)<calculateDistance()){
return 1;
}
if(2<=target.getNumber()&&target.getNumber()<=8&&tileNumber[Util::prevTypeTile(target).getPriority()]>=1&&
tileNumber[Util::nextTypeTile(target).getPriority()]>=1&&distanceAfterCHOW(target,2)<calculateDistance()){
return 2;
}
if(3<=target.getNumber()&&tileNumber[Util::prevTypeTile(Util::prevTypeTile(target)).getPriority()]>=1&&
tileNumber[Util::prevTypeTile(target).getPriority()]>=1&&distanceAfterCHOW(target,3)<calculateDistance()){
return 3;
}
return 0;
}

void CHOW(Tile target,int type){
Tile tile1,tile2,tile3;
if(type==1){
tile1 = target;
tile2 = Util::nextTypeTile(tile1);
tile3 = Util::nextTypeTile(tile2);
}
else if(type==2){
tile2 = target;
tile1 = Util::prevTypeTile(tile2);
tile3 = Util::nextTypeTile(tile2);
}
else{
tile3 = target;
tile2 = Util::prevTypeTile(tile3);
tile1 = Util::prevTypeTile(tile2);
}

std::cout << name << " CHOW " << tile1.getType() << " " << tile2.getType() << " " << tile3.getType() << "\n";
if(tile1!=target){
discard(tile1,false);
}
if(tile2!=target){
discard(tile2,false);
}
if(tile3!=target){
discard(tile3,false);
}
}

Player(){
tileNumber.resize(38);
}
Player(std::string _name):
name(_name){
tileNumber.resize(38);
}
};

Tiles tiles;
bool reversed=false,skipDraw=false;
std::vector<Player> players(MAX_PLAYER);
std::vector<Player>::iterator currentPlayer=players.begin();

namespace Game{
std::vector<Player>::iterator getNextPlayer(std::vector<Player>::iterator targetPlayer){
if(!reversed){
return std::next(targetPlayer)==players.end()?players.begin():std::next(targetPlayer);
}
else{
return targetPlayer==players.begin()?std::prev(players.end()):std::prev(targetPlayer);
}
}

void nextPlayer(){
currentPlayer = getNextPlayer(currentPlayer);
}

void goRound(){
if(!skipDraw){
if(!tiles.canDraw()){
std::cout << "DRAW\n";
exit(0);
}
currentPlayer->draw(tiles);
}
else{
skipDraw = false;
}

if(currentPlayer->specialTileCount()==0&&currentPlayer->calculateDistance()==0){
std::cout << currentPlayer->getName() << " SELFDRAWN\n" << currentPlayer->getName() << " WIN\n";
exit(0);
}

std::vector<Tile>::iterator firstTile=currentPlayer->getTile([](Tile x,Tile y)->bool{
return x.getPriority()>y.getPriority();
});
if(firstTile->isSpecialTile()){
bool doubleRound=false,skipNextRound=false;
if(firstTile->getType()=="PASS"){
skipNextRound = true;
std::cout << currentPlayer->getName() << " OUT PASS " << Game::getNextPlayer(currentPlayer)->getName() << "\n";
}
else if(firstTile->getType()=="REVERSE"){
reversed = !reversed;
}
else if(firstTile->getType()=="DOUBLE"){
doubleRound = true;
}
currentPlayer->discard(firstTile,firstTile->getType()!="PASS");
if(skipNextRound){
nextPlayer();
nextPlayer();
}
else if(!doubleRound){
nextPlayer();
}
return;
}

firstTile = currentPlayer->getTile([&](Tile x,Tile y)->bool{
int disx=currentPlayer->distanceAfterDiscard(x),disy=currentPlayer->distanceAfterDiscard(y);
if(disx==disy){
return x.getPriority()>y.getPriority();
}
return disx<disy;
});
Tile publicTile = *firstTile;
currentPlayer->discard(firstTile);

std::vector<Player>::iterator targetPlayer=getNextPlayer(currentPlayer);
while(targetPlayer!=currentPlayer){
if(targetPlayer->specialTileCount()==0&&targetPlayer->distanceAfterAdd(publicTile)==0){
std::cout << targetPlayer->getName() << " RON\n" << targetPlayer->getName() << " WIN\n";
exit(0);
}
targetPlayer = getNextPlayer(targetPlayer);
}

targetPlayer = getNextPlayer(currentPlayer);
while(targetPlayer!=currentPlayer){
if(targetPlayer->canPONG(publicTile)){
targetPlayer->PONG(publicTile);
skipDraw = true;
currentPlayer = targetPlayer;
return;
}
targetPlayer = getNextPlayer(targetPlayer);
}

if(publicTile.isNumberTile()){
targetPlayer = getNextPlayer(currentPlayer);
int CHOWType=targetPlayer->canCHOW(publicTile);
if(CHOWType!=0){
targetPlayer->CHOW(publicTile,CHOWType);
skipDraw = true;
currentPlayer = targetPlayer;
return;
}
}

nextPlayer();
}
}

int main(){
for(int tilesCount=1;tilesCount<=TILE_NUMBER;tilesCount++){
std::string tileType;
std::cin >> tileType;
tiles.addTile(tileType);
}

std::string currentName="A";
for(int player=1;player<=MAX_PLAYER;player++){
*currentPlayer = Player(currentName);
currentName[0]++;
Game::nextPlayer();
}

for(int range=1;range<=INITIAL_TILE_NUMBER;range++){
for(int player=1;player<=MAX_PLAYER;player++){
currentPlayer->draw(tiles);
Game::nextPlayer();
}
}

while(true){
Game::goRound();
}

return 0;
}
  • 标题: 洛谷 P7147 [THUPC 2021 初赛] 麻将模拟器 题解
  • 作者: Gavin
  • 创建于 : 2025-07-18 16:40:00
  • 更新于 : 2025-07-26 10:01:43
  • 链接: https://gavin-blog.pages.dev/2025/洛谷-p7147-thupc-2021-初赛-麻将模拟器-题解/
  • 版权声明: 本文章采用 CC BY-NC-SA 4.0 进行许可。
目录
洛谷 P7147 [THUPC 2021 初赛] 麻将模拟器 题解